U.S. patent number 10,427,488 [Application Number 15/782,150] was granted by the patent office on 2019-10-01 for method and apparatus for mitigating static loads in components connecting multiple structures.
This patent grant is currently assigned to ClearMotion, Inc.. The grantee listed for this patent is ClearMotion, Inc.. Invention is credited to Marco Giovanardi, Ramkumar Krishnan.
![](/patent/grant/10427488/US10427488-20191001-D00000.png)
![](/patent/grant/10427488/US10427488-20191001-D00001.png)
![](/patent/grant/10427488/US10427488-20191001-D00002.png)
![](/patent/grant/10427488/US10427488-20191001-D00003.png)
![](/patent/grant/10427488/US10427488-20191001-D00004.png)
![](/patent/grant/10427488/US10427488-20191001-D00005.png)
![](/patent/grant/10427488/US10427488-20191001-D00006.png)
![](/patent/grant/10427488/US10427488-20191001-D00007.png)
![](/patent/grant/10427488/US10427488-20191001-D00008.png)
![](/patent/grant/10427488/US10427488-20191001-D00009.png)
![](/patent/grant/10427488/US10427488-20191001-D00010.png)
View All Diagrams
United States Patent |
10,427,488 |
Krishnan , et al. |
October 1, 2019 |
Method and apparatus for mitigating static loads in components
connecting multiple structures
Abstract
An apparatus and method are described where one or more
pre-stressed spring elements are disposed between two structures to
mitigate or cancel the effect of static loads applied to an
component connecting the structures. The apparatus and methods may
be used, for example, to reduce the adverse impact of static loads
on the performance of top-mounts in a suspension system of a
vehicle.
Inventors: |
Krishnan; Ramkumar (Watertown,
MA), Giovanardi; Marco (Melrose, MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
ClearMotion, Inc. |
Woburn |
MA |
US |
|
|
Assignee: |
ClearMotion, Inc. (Billerica,
MA)
|
Family
ID: |
61902566 |
Appl.
No.: |
15/782,150 |
Filed: |
October 12, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180105010 A1 |
Apr 19, 2018 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62407742 |
Oct 13, 2016 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G
17/056 (20130101); B60G 13/003 (20130101); B60G
17/08 (20130101); F16F 9/54 (20130101); B60G
2600/182 (20130101); B60G 2204/128 (20130101); B60G
2202/413 (20130101) |
Current International
Class: |
B60G
17/056 (20060101); F16F 9/54 (20060101); B60G
13/00 (20060101); B60G 17/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Brown; Drew J
Attorney, Agent or Firm: Wolf, Greenfield & Sacks,
P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Patent
Application Ser. No. 62/407,742, filed Oct. 13, 2016, entitled
"Method and Apparatus for Compensating Static Load on a
Suspension-Top Mount," by Krishnan, et al. which is incorporated
herein by reference in its entirety.
Claims
The invention claimed is:
1. A top-mount assembly for attaching a suspension component to a
vehicle body, the top-mount assembly comprising: a top-mount
bracket; a strike plate at least partially surrounded by the top
mount bracket and configured to be attached to a piston rod of the
suspension component; and a resilient material interposed between
the top-mount bracket and the strike plate; wherein the resilient
material has a stiffness that varies as a function of a position of
the strike plate relative to the top-mount bracket, wherein the
stiffness has a first value in a first range of positions of the
strike plate relative to the top-mount bracket, a second value
substantially greater than the first value in a second range of
positions of the strike plate relative to the top-mount bracket,
and a third value substantially greater than the first value in a
third range of positions of the strike plate relative to the
top-mount bracket; wherein application of a predetermined rod force
to the strike plate causes the strike plate to be displaced from a
first position to a second position relative to the top mount
bracket, wherein the second position of the strike plate is more
centrally located within the first range of positions than the
first position of the strike plate.
2. The top mount assembly of 1, wherein the suspension component is
selected from the group consisting of a passive damper, an active
damper, a semi-active dampers, and a magnetorheological damper.
3. The top mount assembly of claim 2, wherein the predetermined rod
force is a force applied by a piston rod of the suspension
component under static conditions.
4. The top mount assembly of claim 1, wherein the resilient
material is at least partially made of an elastomer.
5. The top mount assembly of claim 4, wherein the elastomer
includes rubber.
6. The top mount assembly of claim 1, wherein resilient material is
molded onto the strike plate.
7. The top mount assembly of claim 1, wherein the first value is
less than 1000 newtons per millimeter and the second and third
values are greater than 1000 newtons per millimeter.
8. The top mount assembly of claim 7, wherein the second and the
third values are greater than 1000 newtons per millimeter.
9. The top mount assembly of claim 1, wherein the predetermined rod
force is between 800 newtons and 900 newtons.
10. The top mount assembly of claim 1, wherein the first position
is a neutral position of the strike plate.
11. The top mount assembly of claim 10, wherein when the strike
plate is located at the neutral position, at least a portion of the
resilient material is prestressed.
12. The actuator assembly of claim 1, wherein the static force is
between 800 newtons and 900 newtons.
13. The actuator assembly of claim 1, wherein at the first
position, movement of the strike plate relative to the bracket in
one direction always results in a net force applied to the strike
plate by the resilient material in a first direction and movement
of the strike plate relative to the bracket in an opposite
direction always produces a force in a second direction that is
opposite the first direction.
14. An actuator assembly for a vehicle, the actuator assembly
comprising: a hydraulic actuator that includes: a damper body; a
rod protruding from the damper body; a top mount that includes: a
strike plate that is affixed to the rod; a top-mount bracket at
least partially surrounding the strike plate; and a resilient
material interposed between the top-mount bracket and the strike
plate; wherein the stiffness of the resilient material varies as a
function of position of the strike plate relative to the top-mount
bracket; wherein the stiffness of the resilient material has a
first value in a first range of positions of the strike plate
relative to the top-mount bracket, a second value substantially
greater than the first value in a second range of positions of the
strike plate relative to the top-mount bracket, and a third value
substantially greater than the first value in a third range of
positions of the strike plate relative to the top-mount bracket;
and wherein, under static conditions of the hydraulic actuator, the
piston rod transmits a static force to the strike plate that causes
the strike plate to be displaced from a first position to a second
position relative to the top mount bracket, wherein the second
position of the strike plate is more centrally located within the
first range of positions than the first position of the strike
plate.
15. The actuator assembly of claim 14, wherein the resilient
material is at least partially constructed of an elastomer.
16. The actuator assembly of claim 15, wherein the elastomer
includes rubber.
17. The actuator assembly of claim 14, wherein the resilient
material is molded onto the strike plate.
18. The actuator assembly of claim 14, wherein the first value is
less than 1000 newtons per millimeter and the second and third
values are greater than 1000 newtons per millimeter.
19. A method of assembling an actuator assembly in a vehicle, the
method comprising: attaching a piston rod of a hydraulic actuator
to a strike plate of a top mount, wherein the hydraulic actuator is
configured to apply a force to the strike plate; wherein the top
mount includes the strike plate, a top mount bracket, and a
resilient material interposed between the top-mount bracket and the
strike plate, wherein the stiffness of the resilient material has a
first value in a first range of positions of the strike plate
relative to the top-mount bracket, a second value substantially
greater than the first value in a second range of positions of the
strike plate relative to the top-mount bracket, and a third value
substantially greater than the first value in a third range of
positions of the strike plate relative to the top-mount bracket;
and after attaching the piston rod and with the hydraulic actuator
under static conditions, transmitting a static force from the
piston rod to the strike plate, thereby displacing the strike plate
from neutral first position relative to the top mount bracket to a
second position relative to the top mount bracket, wherein the
second position is more centrally located within the first range of
positions than the first position of the strike plate.
Description
FIELD
Embodiments described herein are related to methods and apparatuses
for compensating static load on a suspension top-mount.
BACKGROUND
Top-mounts are used to mitigate road induced motion to improve
occupant comfort in a vehicle. Top-mounts typically incorporate
elastomeric spring elements that are also able to damp disturbances
that may originate, for example, from vertical wheel motion and
other wheel events and/or road events. Road events may include, for
example, travelling over a pothole, a bump or crack in the road,
and/or other road imperfections as well as events such as
navigating a turn, braking, and/or accelerating.
SUMMARY
In active suspension systems, under static conditions one or more
components of a top-mount assembly may be subject to significant
static force, thereby precluding optimal performance of the
top-mount assembly. The present disclosure describes, inter glia,
various apparatuses and methods that may be used to prevent and/or
at least partially counter-balance a static force that is applied
to one or more components of a top-mount assembly of a vehicle.
In one aspect, a top-mount assembly for attaching a suspension
component to a vehicle body is disclosed. In certain embodiments,
the top-mount assembly may include: a strike plate configured to
attach to a rod of the suspension component; a first set of one or
more first spring elements in contact with the strike plate,
wherein each first spring element applies a first force to the
strike plate in a first direction; a second set of one or more
second spring elements in contact with the strike plate, wherein
each second spring element applies a second force to the strike
plate in a second direction that is opposite the first direction.
In certain embodiments, the second set of one or more spring
elements applies a combined force onto the strike plate of at least
200 N, at least 400 N, at least 600 N, at least 800 N, or at least
1000 N. In certain embodiments, the first direction is
substantially upwards and the second direction is substantially
downwards.
In certain embodiments, the first set of one or more first spring
elements is characterized by a first combined spring constant, and
the second set of one or more second spring elements is
characterized by a second combined spring constant that is less
than the first combined spring constant. Alternatively or
additionally, in certain embodiments the first set of one or more
first spring elements is characterized by a first combined
compliance and the second set of one or more second spring elements
is characterized by a second combined compliance that is greater
than the first combined compliance. In certain embodiments, the
second combined compliance is greater than the first combined
compliance by a factor of at least 2. In certain embodiments, the
second combined compliance is greater than the first combined
compliance by a factor of at least 5. In certain embodiments the
strike plate comprises an opening therethrough, wherein the opening
is adapted to receive a portion of the piston rod. In certain
embodiments, the top-mount assembly may include a bracket
configured to attach to the vehicle body, wherein each first spring
element is interposed between an inner surface of the bracket and a
first face of the strike plate.
In another aspect, a suspension system is disclosed that may
include: a damper assembly comprising a piston rod; a top-mount
assembly comprising: a strike plate attached to the piston rod, a
first set of one or more spring elements in contact with the strike
plate, wherein the first set of one or more spring elements is
characterized by a first combined spring constant; a second set of
one or more spring elements in contact with the strike plate,
wherein the second set of one or more spring elements is
characterized by a second combined spring constant that is less
than the first combined spring constant; wherein the piston rod and
the first set of one or more spring elements are arranged such
that, under static conditions: the second set of one or more spring
elements applies a second combined force to the strike plate in a
first direction, and the piston rod applies a static rod force to
the strike plate in a second direction that is opposite the first
direction, wherein a magnitude of the rod force is substantially
equal to a magnitude of the second combined force. In certain
embodiments, the damper assembly includes a housing defining an
internal volume that is separated, by a piston slidably inserted
into the housing, into a first volume and a second volume. In
certain embodiments, the damper assembly includes a motor/pump that
is in fluid communication with the first volume and/or the second
volume and that is configured to controllably vary a pressure
differential between the first volume and the second volume.
In another aspect, a top-mount assembly for attaching a suspension
component to a vehicle body is disclosed, the top-mount assembly
including a top-mount bracket; a strike plate located within the
top-mount bracket, wherein the strike plate is movable relative to
the top-mount bracket from a first position to a second position; a
first spring element characterized by a first spring constant; a
second spring element characterized by a second spring constant,
wherein the first spring element and the second spring element
couple the top-mount bracket to the strike plate; and wherein the
first spring element and the second spring element are functionally
arranged in parallel.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are not intended to be drawn to scale. In
the drawings, each identical or nearly identical component that is
illustrated in various figures may be represented by a like
numeral. For purposes of clarity, not every component may be
labeled in every drawing. In the drawings:
FIG. 1 is a schematic representation of a top-mount assembly.
FIG. 2 is a schematic representation of the top-mount assembly of
FIG. 1 exposed to a piston rod force under static conditions.
FIG. 3 is a schematic representation of an embodiment of a
top-mount with a spring element that is pre-stressed during
manufacture.
FIG. 4 is a free-body diagram of the strike plate of the top-mount
in FIG. 3 under pre-installation loading.
FIG. 5 is a schematic representation of the top-mount of FIG. 3
attached to a piston rod of a suspension damper assembly.
FIG. 6 is a free-body diagram of the strike plate of FIG. 5 under
static loading conditions where the force applied by the
pre-stressed spring element at least partially cancels the
piston-rod force.
FIG. 7 is a schematic representation of an embodiment of a
top-mount assembly with an elastomeric unit that performs the
function of three spring elements.
FIG. 8 is a schematic representation of the top-mount of FIG. 7
where the top and bottom halves are attached and at least two of
the spring elements are pre-stressed.
FIG. 9 is a free-body diagram of the strike plate of the top-mount
of FIG. 8.
FIG. 10 is a schematic representation of the top-mount assembly of
FIG. 8 attached to a piston rod of a suspension damper assembly
where the piston rod applies a force on the strike plate under
static conditions.
FIG. 11 is a free-body diagram of the strike plate of the top-mount
of FIG. 10.
FIG. 12 is a schematic representation of an embodiment of a vehicle
suspension assembly where a spring element located between the
top-mount bracket and the piston rod is used to at least partially
cancel the force applied by the piston rod under static
conditions.
FIG. 13 is a partially sectioned CAD drawing of the embodiment
shown in FIG. 12.
FIG. 14 is a partially sectioned perspective CAD drawing of the
embodiment of FIG. 13.
FIG. 15 is a schematic representation of another embodiment of a
vehicle suspension assembly where a spring element located between
the top-mount bracket and the piston rod is used to at least
partially cancel the force applied by the piston rod under static
conditions.
FIG. 16 is a partially sectioned CAD drawing of the embodiment
shown in FIG. 15.
FIG. 17 is a partially sectioned perspective CAD drawing of the
embodiment of FIG. 16.
FIG. 18 illustrates an exemplary force-displacement curve.
DETAILED DESCRIPTION
The inventors have recognized that because of elevated operating
pressure in certain suspension damper assemblies, such as is the
case in active suspension systems, the operation of top-mounts or
other compliant attachment devices that are interposed between
damper assemblies and other portions of a vehicle, such as the
vehicle body or wheel assembly, may be compromised. For example,
these elevated pressures may lead to an increased static loading of
a top-mount, or other compliant attachment device, which may cause
these devices to be strained to such a degree that they operate in
an undesirable stiffness range. For example, a top-mount may
undergo sufficient strain due to static loading that it becomes
undesirably stiff. Under these circumstances, when a dynamic load
is applied, the top-mount does not have sufficient compliance as
would normally be desired and/or its compliance may become highly
non-linear in at least one direction. This may cause the top-mount
to become less effective in damping out road disturbances.
Accordingly, the inventors have recognized the benefits associated
with methods and apparatus that modify the operation of a
top-mount, or other compliant attachment device, such that such
static loading is at least partially counteracted, thereby allowing
the top mount to operate in a range where the system compliance is
in a more desirable operating range and/or the compliant attachment
devices may otherwise exhibit a more desired behavior.
Typically, a suspension system damper assembly is mounted in a
vehicle with the rod facing up in a vertical or near vertical
direction. In some embodiments, the damper assembly may be mounted
in a near horizontal or horizontal direction, in an "inverted"
configuration, i.e. with the rod facing down and the damper body
facing up, and/or where the suspension spring is co-located and
concentric with the damper (typically called a "strut"
assembly).
For the sake of clarity, in the embodiments described below,
reference is made only to top-mounts. However, unless the context
precludes such an interpretation, it should be understood that the
current disclosure may be applied to any appropriate compliant
attachment device or isolator between any two structures including
but not limited to: a compliant isolating bushing, a lower bushing
between a damper body of a suspension system and a wheel assembly,
a compliant bushing between a damper piston rod of a suspension
system and a wheel assembly when the damper is in and inverted
rod-down arrangement.
In one embodiment, a top-mount assembly of a suspension system of a
vehicle may include a strike plate that is configured to attach to
a rod of a damper assembly and a top-mount bracket that is
configured to attach to the vehicle body. In some instances, the
strike plate may be attached to the damper assembly via a
connection to the piston rod. As discussed previously, the damper
assembly may be located between, and attached to, the top-mount
assembly and a wheel assembly of the vehicle. In certain
embodiments, the damper assembly may be interposed between the
wheel assembly of the vehicle and the top-mount assembly, such that
forces applied to the wheel assembly (e.g., because of driving over
a road surface) may be transferred to the top mount assembly via
the damper assembly.
Appropriate dampers for use in the damper assemblies described in
the current disclosure, include, but are not limited to, passive
dampers (e.g., hydraulic passive dampers), active dampers,
semi-active dampers, magnetorheological dampers, and actuators
(e.g., a hydraulic actuator). In certain embodiments, an active
damper may include an actuator (e.g., a hydraulic actuator) that is
capable of applying an active commanded force (e.g., a force in the
direction of motion) onto the vehicle body (e.g., by means of the
top-mount assembly and to the vehicle body) and/or the wheel
assembly. The descriptions in this disclosure apply in much the
same way if the damper assembly is mounted in the "traditional"
rod-up direction, i.e. with the piston rod extending upwards or
substantially upwards, relative to a bottom surface of the vehicle
facing the ground, from the damper assembly body; in an "inverted"
configuration, i.e. with the piston rod extending downward or
substantially downward, relative to a bottom surface of the vehicle
facing the ground, from the damper assembly body; as well as for
systems where the suspension coil spring is co-located and
concentric with the damper, i.e. a "strut" assembly. While specific
orientations of a damper assembly have been noted above, it should
be understood that the current disclosure may be used with a damper
assembly, and/or actuator, arranged in any appropriate orientation
as the disclosure is not so limited.
During operation, a rod (e.g., a piston rod) of a damper (e.g., an
actuator) may be used to apply a first force directed along a
longitudinal axis of the piston rod and in a first direction on the
strike plate of a top mount assembly. For example, the first
direction may be upward or approximately upward, or the first
direction may be downward or approximately downward direction. In a
passive suspension system, both a magnitude of the first force and
the first direction are based on a stimulus force that is imparted
onto the wheel assembly of the vehicle by a road surface. On the
other hand, in an active suspension, the magnitude and the first
direction of the first force may be based on the stimulus force
(e.g., an active suspension system may be configured to operate as
a passive suspension system), or they may be commanded (e.g., by a
processor) independently of the stimulus force provided by the road
surface.
In the case of a hydraulic damper (e.g., a hydraulic actuator),
under static conditions (e.g., in the absence of a stimulus force
and/or in the absence of a commanded force), the rod may apply a
static force having a static direction such as, for example,
upwards or approximately upwards. Such static force may arise as a
result of geometrical considerations of a piston and the piston rod
of the hydraulic damper. Application of the static force to the
strike plate of the top-mount assembly by the rod of the damper may
be referred to as "static loading."
In certain embodiments, the strike plate may be enclosed by a
top-mount bracket. In certain embodiments, a first spring element
may be located between the top-mount bracket and the strike plate.
The first spring element may be pre-stressed during manufacture
and/or assembly such that it applies a prestress force on the
strike plate in a direction substantially opposite to the static
direction. A second spring element is located between the strike
plate and the top-mount bracket. Under static conditions, the
second force applied by the first spring element may counter
balance at least a portion of the static force applied on the
strike plate by the rod of the damper.
A spring element may refer to any element that deforms by an amount
that is proportional to an applied force and, upon removal of the
applied force, regains or approximately regains its original
dimensions. Examples of spring elements include coil springs,
conical springs, and pieces of resilient material such as, for
example, elastomers (e.g., rubber). It is understood that a single
physical piece of resilient material (e.g., rubber) may comprise a
plurality of spring elements.
Having discussed the current disclosure generally above, certain
exemplary embodiments are now described in more detail in relation
to the figures to provide an overall understanding of the
principles of the structure, function, manufacture, and use of the
system and methods disclosed herein for a top-mount system.
However, it should be understood by one of ordinary skill in the
art that the systems, methods and examples described herein and
illustrated in the accompanying drawings are non-limiting exemplary
embodiments. Further, it should be understood that the various
features illustrated or described in connection with the different
exemplary embodiments described herein may be combined with
features of other embodiments and the features may be used
individually, singularly and/or in various combinations as the
disclosure is not so limited. Such modifications are intended to be
included within the scope of the present invention.
The schematic in FIG. 1 illustrates a vehicle suspension assembly 1
that includes a top-mount assembly 2, with a top-mount bracket 3
and top-mount strike plate 4. The top mount bracket at least
partially encompasses a flat disk shaped, or otherwise
appropriately shaped, top-mount strike plate 4. The strike plate
typically includes an opening therethrough that is configured to
receive a portion a rod 6 of the damper assembly 7.
The rod 6 may be a piston rod that is attached to a piston (not
shown) of the damper assembly 7, or, as in the case of an inverted
configuration, it may be a rod 6 that is attached to a housing of
the damper assembly 7. An exemplary damper assembly may include a
housing defining an internal volume that is separated into a first
volume and a second volume by a piston slidably inserted into the
housing, and a piston rod attached to the piston. Additionally, in
certain embodiments the damper assembly may further include a
motor/pump in fluid communication with the first volume and second
volume, wherein the motor/pump may be configured to controllably
vary a pressure differential between fluid in the first volume and
fluid in the second volume. In these embodiments, the damper
assembly may be referred to as an actuator or an actuator assembly.
Static conditions of such an actuator may refer to conditions when
pressure of fluid in the first volume is equal to pressure of fluid
in the second volume, such that the pressure differential is
zero.
The rod may be securely attached to the strike plate using a
fastener such as, for example, a nut or any other appropriate
fastening mechanism. In the embodiment in FIG. 1, a set of spring
elements 5a-d, each of which may operate under tension or
compression, are interposed between the strike plate and the
top-mount bracket 3. As illustrated, the set of spring elements
5a-d may include upper spring elements 5a-b and lower spring
elements 5c-d. In the illustrated embodiment, the upper spring
elements 5a-b are interposed between an inner surface of the
top-mount bracket 3 and a top face of the strike plate 4, while the
lower spring elements 5c-d are interposed between the inner surface
of the top mount bracket 3 and a bottom face of the strike plate 4.
It is understood that the set of spring elements 5a-d may be
embodied in a single piece of resilient material, or in various
pieces of resilient material, located in the volume defined by the
inner surface of the top mount bracket 3 and the strike plate 4. In
certain embodiments, this may be accomplished by molding the
resilient material onto the strike plate 4.
Spring constants of each of the spring elements 5a-d may be
combined using equations known in the art to determine a single,
combined spring constant. For example, a set of n spring elements
oriented in a parallel arrangement may be characterized by a single
combined spring element using the equation
k.sub.combined=k.sub.1+k.sub.2+k.sub.3 . . . +k.sub.n, where
k.sub.combined represents the combined spring constant and k.sub.1,
k.sub.2, k.sub.3, k.sub.n represent a respective spring constant of
spring elements 1, 2, 3, and n. Likewise, a set of n spring
elements oriented in a series arrangement may be characterized by a
single combined spring element using the equation
(k.sub.combined).sup.-1=(k.sub.1).sup.-1+(k.sub.2).sup.-1+(k.sub.3).sup.--
1 . . . +(k.sub.n).sup.-1. As would be recognized by one of
ordinary skill in the art, these equations and principles may be
modified appropriately such that any set of spring elements
oriented in any manner may be characterized by a single combined
spring constant and/or a combined compliance. Likewise, individual
forces applied by each of the spring elements 5a-d onto the strike
plate 4 may be summed to determine a single combined force that is
applied by the set of spring elements 5a-d onto the strike plate
4.
Continuing with FIG. 1, the strike plate may be attached to a top
end of the rod 6 (e.g., the piston rod) of a damper assembly 7. The
damper assembly 7 may be disposed between the top-mount assembly 2
and a wheel assembly 8 of a vehicle (not shown). In active
suspension systems, the damper assembly 7 may include an actuator.
The top-mount assembly may be securely attached to the vehicle body
by using one or more flanges 9 and attachment devices (not shown),
such as for example, bolts or threaded studs. Typically, under
static conditions, i.e. when the vehicle is stopped on a flat
horizontal surface and, in the case of an active suspension system,
no force is commanded of the actuator, the weight of the vehicle is
supported primarily by a coil spring 10 that may be interposed
between the top-mount assembly 2 and a spring perch 12. In various
embodiments, the spring perch 12 may be attached to a bottom end of
the damper body 7a or may be attached to the wheel assembly 8.
Prior to attachment of the rod 6 to the strike plate 4, the strike
plate 4 may be located at a neutral position 11 relative to the
top-mount bracket 3. In the neutral position 11, the combined force
applied by the set of spring elements 5a-d onto the strike plate
may be approximately equal in magnitude to the weight of the strike
plate, and in an opposite direction. In certain embodiments, the
weight of the strike plate and stiffness of each of the spring
elements 5a-d may be chosen such that, when the strike plate is
located in its neutral position 11, one or more of the spring
elements are in an unstressed or nearly unstressed state. However,
various levels of stress may also be present as the disclosure is
not so limited. Following attachment of the rod 6 to the strike
plate 4, the rod 6 may apply a static force to the strike plate 4
as discussed above. This static force may cause the strike plate 4
to shift its position away from the neutral position 11. As would
be recognized by one of ordinary skill in the art, the magnitude of
the static force may be related to the operating (or equilibrium)
pressure of the damper.
In passive suspension systems, under static conditions, the static
force applied on the strike plate 4 by the rod 6 is minimal such
as, for example, less than 20 N, less than 50 N, less than 100 N,
or less than 500 N. This may be due, at least in part, to the
relatively low operating pressures utilized by passive dampers. In
these cases, under static conditions, the combined force applied on
the strike plate 4 by the set of spring elements 5a-d and the
static force applied on the strike plate 4 by the rod 6 may be in
equilibrium such that the strike plate remains at or near its
neutral position 11 in FIG. 1.
When a position of the strike plate 4 relative to the top-mount
bracket 3 deviates from the neutral position 11, each of the spring
elements 5a-d become compressed or extended. For example, in the
embodiment of FIG. 1, upward movement of the strike plate 4 with
respect to the neutral position 11 may cause the upper spring
elements 5a-b to be under compression and/or causes the lower
spring elements 5c-d to be under tension. The set of spring
elements 5a-d are typically designed to exhibit effectively a
constant combined compliance or combined stiffness over a first
range of positions of the strike plate 4 relative to the top-mount
bracket 3. Beyond that range, over a second range of positions, the
combined compliance of the set of spring elements 5a-d is typically
reduced (i.e., the combined stiffness is increased) in order to
limit relative motion within the top-mount assembly, for example,
to avoid damage to the top-mount. However, in this second range of
reduced compliance, the top-mount is substantially stiffer which
may lead to a harsher ride in the vehicle. In some embodiments, it
is, therefore, desirable to minimize operation of the top mount in
this second position range.
The above behavior is illustrated by the force-position curve shown
in FIG. 18. The x-axis of the plot represents position of the
strike plate 4 relative to the top mount bracket 3. The origin 1803
of the curve 1801 represents the neutral position of the strike
plate 4; positive x-values represent deviation of a position of the
strike plate 4 in a first direction (e.g., in the upwards direction
of FIG. 18) with respect to the neutral position 11; and negative
x-values represent deviation of a position of the strike plate 4 in
a second direction (e.g., downwards direction of FIG. 18) with
respect to the neutral position 11. "Position" of the strike plate
4, or "strike plate position," is understood to refer to position
of the strike plate 4 relative to the top-mount bracket 3. The
y-axis in FIG. 18 represents the combined force applied by the set
of spring elements 5a-d on the strike plate 4 when the strike plate
4 is located in a corresponding position given by the x-axis. The
combined stiffness of the set of spring elements 5a-d is given by
the derivative of the curve shown in FIG. 18 and, as discussed
above, may depend on the position of the strike plate 4 relative to
the neural position 11.
In the illustrated example, when the strike plate 4 is located at
its neutral position 1803 (e.g., x=0 in the curve shown in FIG.
18), the combined force applied by the set of spring elements 5a-d
is zero or effectively zero. This indicates that the weight of the
strike plate is minimal or negligible as compared to the combined
stiffness of the set of spring elements. Further, the combined
stiffness of the set of spring elements (given by the derivative of
the curve) for a first range 1805 of positions (e.g., a first range
of positions located adjacent to the neutral position 1803), may be
relatively low (e.g., less than 100 N/mm, less than 500 N/mm, less
than 1,000 N/mm). Further, the combined stiffness of the set of
spring elements within the first range 1805 may be effectively
constant (e.g., the combined stiffness at any point within the
first range may vary no more than 2%, more than 5%, more than 10%,
or more than 20% of the mean over the range). Upon deviation of the
strike plate position beyond a first threshold 1807 in the first
direction, the combined stiffness of the set of spring elements may
increase substantially and become relatively high (e.g., greater
than 100 N/mm, greater than 500 N/mm, greater than 1000 N/mm) for a
second range of positions 1809. Likewise, upon deviation of the
strike plate position beyond a second threshold 1811 in the second
direction, the combined stiffness of the set of spring elements may
increase substantially and become relatively high (e.g., greater
than 100 N/mm, greater than 500 N/mm, greater than 1000 N/mm) for a
third range of positions 1813.
In some embodiments, such as active suspension actuators, the
operating pressure in the damper body may be elevated to, for
example, several hundred pounds per square inch. The applicant has
discovered that this elevated pressure results in a resultant
static force on the damper piston that is conveyed to the piston
rod and the strike plate 4. FIG. 2 illustrates a suspension
assembly 20, which includes a damper housing 21a with an elevated
operating pressure. Under static conditions, the elevated operating
pressure results in a significant static force F.sub.s 23 that is
applied to the strike plate 4 of the top-mount assembly 2. In some
embodiments, the elevated system pressure may be, for example,
between 400-500 psi. This may result in a static force, F.sub.s,
of, for example, between 800 N-900 N or greater depending on the
characteristic dimensions of the piston and piston rod. It is noted
that elevated operating pressures, both above and below the above
range, and above and below 800 N-900 N may be used as the
disclosure is not so limited.
FIG. 2 depicts the damper system of FIG. 1 in which the damper body
21a is charged to an elevated pressure. In this depicted
configuration, the static force 23, which scales with the operating
pressure of the damper body 21a, causes the strike plate 4 to shift
away from the neutral position 11 until the combined force applied
to the strike plate 4 by the set of the spring elements 5a-d
sufficiently counteracts the static force, F.sub.s, applied to the
piston rod by the damper. As a result of the static force applied
on the strike plate, the strike plate finds a new position,
referred to herein as the loaded position 24. In the loaded
position 24, the upper spring elements 5a-b are compressed and the
lower spring elements 5c-d are extended. While four spring elements
have been depicted in the figure, it should be understood that any
number of spring elements may be disposed between the strike plate
and the bracket as the disclosure is not so limited.
In some embodiments, the static force Fs may be sufficiently large,
such that at the loaded position 24, the compliance of one or more
of the spring elements is decreased and one or more of the spring
elements becomes sufficiently stiff to reduce the effectiveness of
the top-mount in responding to disturbances that may be transmitted
up the piston rod to the vehicle body. In other words, referring to
FIG. 18, the loaded position 24 may lie outside of, or near the
edge of, the first range 1805 of positions, thereby impeding
overall performance of the top-mount.
FIG. 3 illustrates another embodiment of a top-mount assembly 30
prior to attachment to a rod of a damper. The illustrated top-mount
assembly includes a strike plate 31 and a first set of one or more
spring elements 32a-d, each of which is interposed between the
strike plate 31 and top-mount bracket 33. In addition, the top
mount assembly also includes a second set of one or more spring
elements 34 that are used to pre-stress the top-mount assembly. In
certain embodiments, the second set of one or more spring elements
34 may be functionally arranged in parallel to the first set of
spring elements 32a-d. Two spring elements are said to be
functionally arranged in parallel if the combined force applied by
the two spring elements is equal to the sum of the individual
forces applied by each spring element.
The pre-stress force applied by the second set of spring elements
34 moves the strike plate to a position, referred to as a
pre-stressed position, thereby compressing lower spring elements
32c-d while extending upper spring elements 32a-32b. An exemplary
arrangement of forces acting on the strike plate 31 in the
pre-stressed position are shown in FIG. 4. Disregarding the weight
of the strike plate 31 as negligible compared to the pre-stress
force, a magnitude of the pre-stress force applied to the strike
plate by the second set of spring elements, F34, is equal to the
magnitude of the combined force applied to the strike plate by the
first set of spring elements, F32a+F32b+F32c+F32d.
The inventors have recognized that, in certain embodiments, it may
be advantageous to design the top mount assembly (e.g., to select
spring elements with appropriate spring constants) such that a
combined compliance second set of spring elements is greater than a
combined compliance of the first set of spring elements 32a-d. If
the second set of spring elements have a combined stiffness that
exceeds that of the first set of spring elements, then vibrations
of the rod of the damper could be undesirably transferred to the
vehicle body through the second set of spring elements. By
designing the system such that the second set of spring elements is
substantially more compliant than the first set of spring elements,
vibrations of the piston rod may be partially absorbed or damped by
the first set of spring elements without being fully transmitted
into the vehicle body. In some embodiments, the combined compliance
of the second set of spring elements 34 is greater than the
combined compliance of the first set of spring elements 32a-d by a
factor of at least 2. In some embodiments, the combined compliance
of the second set of spring elements 34 may be greater than the
combined compliance of the first set of spring elements 32a-d by a
factor of at least 5 or a factor of at least 10. As would be
recognized by one of skill in the art, spring constant and/or
compliance of a spring element may be varied using a variety of
techniques including, for example, by varying material of
construction and/or by varying geometry (e.g., cross-sections) of
the spring elements.
The combined compliance of the second set of springs may be
selected to be any convenient value as the disclosure is not so
limited. However, embodiments, in which the second set of spring
elements has a combined compliance that is less than or equal to
the other spring elements are also contemplated.
In some embodiments, the top-mount assembly in FIG. 3 may be
pre-stressed during the manufacturing process or alternatively or
additionally during the assembly process of the suspension
system.
FIG. 5 illustrates the top-mount assembly of FIG. 3 following
attachment to a rod 21 of a damper assembly 22. As discussed
elsewhere herein, the operating pressure of damper body 22a causes
the rod 21 to apply a static force on the strike plate 31.
In some embodiments, the second set of spring elements 34 may be
designed such that, due to the attachment of the strike plate to
the rod 21, static force 23, F.sub.s, applied to the strike plate
by the rod may cause the strike plate 31 to move to a loaded
position that falls within the range where the combined compliance
(or combined stiffness) of the first set of spring elements 32a-d
is substantially constant. For example, referring to FIG. 18, the
pre-stressed position may fall outside of, or near the limits of,
the first range 1805 of positions. Attaching the rod of the damper
to the strike plate, thereby applying the static force to the
strike plate, may shift the position of the strike plate to within,
or to a more central point within, the first range 1805 of
positions.
The operating pressure in the damper (and, therefore, the static
force applied by the rod of the damper) and/or the pre-stress force
applied by the second set of spring elements 34 may be selected so
that when the static force is transmitted to the strike plate
(under static conditions) by the rod, the strike plate is moved to
a loaded position that is the same as or approximately the same as
its neutral position 11. This may be accomplished by selecting an
operating pressure and a second set of spring elements wherein the
pre-stress force applied to the strike plate by the second set of
spring elements 34 substantially balances (e.g., has a magnitude
equal to or substantially equal to, and a direction opposite to)
the static force F.sub.s applied to the strike plate by the rod.
This force balance is illustrated in FIG. 6. As illustrated by the
free-body diagram shown in FIG. 6 of strike plate 31, under static
conditions, the combined force applied by the second set of spring
element 34 may balance the static force applied by the rod 21. In
this exemplary case, the combined force of the first set of spring
elements 32a-d ranges from zero or approximately zero (that is, the
first set of spring elements 32a-d is effectively unstressed) to
approximately equal to the weight of the strike plate. The static
force applied by the rod may range from 700 N to 2000 N, although
static forces greater and smaller that this range are contemplated
as the disclosure is not so limited. As used herein, two values are
said to be substantially equal if the absolute value of the
difference between the two values is no greater than 5%, no greater
than 10%, no greater than 15%, no greater than 20%, no greater than
25%, or no greater than 30% of the larger of the two values.
In some embodiments, upon attaching the rod of the damper, the
strike plate is moved to a loaded position near its neutral
position, and the first set spring elements 32a-d of FIG. 5 operate
in a region of effectively constant compliance (or effectively
constant stiffness) under normal operating conditions. That is,
referring to FIG. 18, the loaded position may fall within the first
range 1805 of positions. In one embodiment, normal operating
conditions may be considered conditions where the damper exerts a
force onto the strike plate that does not typically exceed .+-.1000
N, 1250 N, 1500 N, 2000 N, and 3000 N. However, embodiments in
which damper forces both greater and smaller than those noted above
are also contemplated.
The top-mount assembly 30 may be securely attached to a vehicle
body by means of, for example, one or more flanges 41, and/or rims,
collars, ribs, or other projections that can be used for this
purpose. The top-mount assembly may also be attached to the vehicle
body by means of threaded studs that protrude from the top-mount
bracket 33. In certain embodiments, the top-mount bracket 33 may
comprise a top portion and a bottom portion configured to be
attached to the upper bracket.
FIG. 7 illustrates one embodiment of a top-mount assembly 50 with a
two-piece bracket. The bottom portion 51 of the bracket includes a
central bowl-shaped hub with flange 51a extending radially
outwardly from the rim of the top opening of the hub. The top
portion 52 of the bracket may be a mirror image of the lower
portion 51 of the bracket, and may also include a radially
outwardly extending flange 52a that surrounds the rim of the lower
opening in the top portion 52 of the top-mount.
The depicted embodiment of a top-mount assembly 50 may also include
a strike plate 53 with a centrally located through-hole 54. The
strike plate 53 may be partially embedded in an annular elastomeric
member 55 that performs as the set of spring elements 56, 57, and
58. Elastomeric materials may include, for example, polyurethanes,
viscoelastic materials, reinforced rubber, filled silicone and
polymers/elastomers (filling may be with, for example, nylon,
metal, plastic, different material fibers, etc.). The spring
elements 56, 57, and 58, shown in FIG. 7 therefore form a single
physical unit, but may be considered separate spring elements.
Further, in some embodiments, each spring element may have a
different or the same material composition as the other spring
elements. In some embodiments, one or more of the elastomeric
spring elements may include non-elastomeric materials such as
steel, hard plastics, and metals. The non-elastomeric substances
may include various types of springs such as, for example,
Belleville spring washers, coil springs, bellows, etc.
In certain embodiments, as illustrated, the elastomeric member 55
may be annular and the strike plate may be located in an internal
cavity at least partially defined by an inner surface of the
elastomeric member 55. The elastomeric member 55 may include an
annular body. The annular body may include a first portion
interposed between a lower face of the strike plate 53 and an inner
surface of the bottom portion 51 of the bracket. The first portion
of the annular body may act as the spring elements 32c-d from FIG.
3. The annular body may further additionally include a second
portion interposed between an upper face of the strike plate 53 and
an inner surface of the top portion 52 of the bracket. The second
portion of the annular body may act as the spring elements 32a-b
from FIG. 3. The first and second portions of annular body may be
in physical contact with, or physically attached to, the strike
plate. Thus, the first and/or second portions of the annular body
may act as the first set of spring elements as described with
respect to FIG. 3 and/or FIG. 5. The annular body may be sized such
that, upon attachment of the top portion 52 of the bracket to the
bottom portion 51 of the bracket, the annular body is in physical
contact with the inner surface of the top portion of the bracket,
the inner surface of the bottom portion of the bracket, and the
strike plate.
The elastomeric member 55 may further include a protruding portion
58 interposed between the upper face of the strike plate 53 and the
inner surface of the top portion 52 of the bracket. The protruding
portion may be dimensioned such that, upon attachment of the top
portion 52 of the bracket to the bottom portion 51 of the bracket,
the protruding portion becomes substantially compressed (e.g.,
substantially compressed relative to its unstressed dimension). For
example, FIG. 7 illustrates the top mount assembly 50 prior to
assembly of the top mount bracket (e.g., prior to attachment of the
upper portion 52 of the bracket to the lower portion 51 of the
bracket), while FIG. 8 illustrates the same top mount assembly
following assembly of the top mount bracket (e.g., after attachment
of the upper portion 52 of the bracket to the lower portion 51 of
the bracket). As can be seen by comparing the dimension of the
protruding portion 58 in FIG. 7 and FIG. 8, following assembly of
the top-mount bracket, the protruding portion is substantially
compressed. In response to the compression, the protruding portion
imparts a restoring force on the top mount bracket in a first
direction (e.g., upwards) and on the strike plate in a second
direction (e.g., downwards). In other words, the protruding portion
58 of the elastomeric member 55 may serve as the second set of
spring elements described in relation to FIG. 3 and/or FIG. 5. The
restoring force applied by the protruding portion 58 of the
elastomeric member 55 applies the pre-stress force to the strike
plate.
Alternatively or additionally, pre-stress force can be applied to
the strike plate via a variety of manufacturing methods. For
example, in certain embodiments, the strike plate may be held at a
first position below its neutral position, and an elastomeric
precursor may be poured into a first volume defined by the upper
face of the strike plate and the inner surface of the top portion
of the bracket. The elastomeric precursor may be cured or otherwise
reacted to yield a first elastomeric material in the first volume.
After the first elastomeric material is formed in the first volume,
the position of the strike plate may be raised relative to the
first position and held in place (e.g., using a clamp or similar
device), thereby compressing the first elastomeric material. While
holding the strike plate in the raised position, elastomeric
precursor may then be poured into a second volume defined by the
bottom face of the strike plate and the inner surface of the bottom
portion of the bracket. The elastomeric precursor in the second
volume may then be cured or otherwise reacted to yield a second
elastomeric material in the second volume. Even upon releasing the
strike plate, the first elastomeric material is therefore
maintained in a state of residual compression, and reacts by
applying a restoring force onto the strike plate that acts as the
above-described pre-stress force. Alternatively or additionally,
the curing process may be modified, as known in the art, to impart
various residual compressive or tensile stresses into the
elastomeric member.
FIG. 9 shows the free-body diagram of the strike plate 53 of FIG.
8. F.sub.1 is the force applied by the spring element 58 and
F.sub.2 is the force applied by the spring element 56. In this
embodiment, spring element 57 is unstressed or lightly stressed and
applies negligible force on the strike plate.
In FIG. 10, the threaded end of the piston rod 61 of a damper (not
shown) is received in centrally located through-hole 54 and
attached to the strike plate 53 by means of a nut 62. The strike
plate is held securely between the nut 62 and the radially
extending annular shoulder 63 of piston rod 61. In some
embodiments, the force applied to the strike plate by the piston
rod is equal and opposite to the force applied by the spring
element 58.
As shown in the free-body diagram in FIG. 11, the protruding
portion 58 may be designed (e.g., by selecting appropriate
dimensions and material properties) such that, following assembly
of the top-mount bracket and attachment of the rod of the damper,
the protruding portion 58 applies a force onto the strike plate 53
that at least partially counterbalances the static force applied by
the rod of the damper. In certain embodiments, under static
conditions the spring elements 56 and 57 are unstressed.
In some embodiments, the forces F.sub.1 and F.sub.s substantially,
but not fully, cancel each other and as a result, a small amount of
residual stress may remain in spring element 56. Substantial
cancellation may be greater than 90%, greater than 70%, greater
than 50% or any other convenient percentage less than these
percentages, as this disclosure is not so limited.
In some embodiments, a spring constant of the spring element 58 may
be substantially less than the combined spring constant of the
other spring elements interposed between the strike plate and the
bracket. A substantially smaller spring constant of a spring
element is one that is 10% or less of the spring constant of a
second spring element. In some embodiments, a substantially smaller
spring constant is one that 25% or less, 50% or less, or 75% or
less of the spring constant of another element or any other
convenient percentage, as this disclosure is not so limited.
In the embodiment in FIG. 10, balancing the force F.sub.s of the
piston rod 61 with the force applied by spring element 58 allows
the other spring elements to be substantially or completely
unstressed after the strike plate is attached to the piston
rod.
In the embodiment shown in FIG. 10, by balancing the piston rod
force with the force in spring element 58, spring elements 56 and
57 predominantly operate in a largely constant range of their
compliance, meaning that the compliance does not change, for
example, by more than 2%, 5%, 10%, 20% in extension and/or
compression.
FIG. 12 illustrates an embodiment of a vehicle suspension assembly
120 with top-mount assembly 121. The damper 122 includes a piston
(not shown) and piston rod 123. The damper 122 is interposed
between a wheel assembly 124 of a vehicle (not shown) and top-mount
assembly 121. In the embodiment in FIG. 12, a suspension coil
spring 125 is interposed between the top-mount bracket 126 and a
lower spring perch 127 that is fixedly attached to the damper
housing 128. Spring element 129 is pre-stressed during the
manufacture of the top-mount assembly 121 or when assembling the
vehicle suspension assembly 120. Spring element 129 is interposed
between the top-mount bracket 126 and disc shaped plate 131a. Plate
131a has a centrally located through hole 131 that receives the
upper portion of piston rod 123. Plate 131a may be secured against
annular radially extending shoulder 132 by the force in spring
element 129. Alternatively or additionally, plate 131a may be
fixedly attached to the piston rod 123 by, for example, welding
and/or utilizing an interference fit between the inner diameter of
through hole 131 and the outer diameter of the upper portion of
piston rod 123. It is understood that shapes of the strike plate
and the bracket other than those shown in FIG. 12 are contemplated
as the disclosure is not so limited.
During manufacture and/or assembly, the spring element 129 may be
compressed to produce a force that opposes, and at least partially
cancels, the force applied by the piston rod on the top-mount
assembly.
FIG. 13 depicts one embodiment of a top-mount assembly and piston
rod of the embodiment in FIG. 12. In FIG. 13, the top-mount
assembly and the rod are positioned to be joined together. When the
top-mount assembly 140 and piston rod 141 are joined together, at
least spring element 143 and spring element 142 are stressed to
apply opposite forces on strike plate 145. When the damper (not
shown) is charged so that it applies a force on the piston rod in
the upward direction, that force is at least partially balanced by
the force applied by spring element 142 and spring element 143 is
at least partially off-loaded. FIG. 14 illustrates a perspective
section view of the top-mount assembly and piston rod shown in FIG.
13.
FIG. 15 illustrates another embodiment of a vehicle suspension
assembly 150 with a top-mount assembly 151. The damper 152 includes
a piston (not shown) and a rod 153. The top-mount assembly 151
includes a top-mount bracket 156 and a strike plate. The top-mount
bracket may be configured to attach to a vehicle body and the
strike plate may be configured to attach to the rod 153. The top
mount bracket 156 includes an upper bracket portion and a lower
bracket portion. The lower bracket portion may include an
intermediate bracket member and a lower bracket member. In certain
embodiments, the upper bracket portion may be an inverted cup. The
strike plate may be located in a cavity at least partially defined
by the lower bracket member and the intermediate bracket member. A
first set of spring elements may include one or more lower spring
elements interposed between a bottom face of the strike plate and
the lower bracket member, and/or one or more intermediate spring
elements interposed between a top face of the strike plate and the
intermediate bracket member. In certain embodiments, the top mount
assembly may include a second set of one or more spring elements.
The second set of one or more spring elements may include one or
more upper spring elements arranged such that each upper spring
element is capable of applying a force onto the upper bracket
portion and at least one of the strike plate and the rod. In
certain embodiments, the top mount assembly 151 may include an
anchor 157 that is physically attached to at least one of the
strike plate and the piston rod. In certain embodiments, the second
set of spring elements may include an upper spring element 159 that
is interposed between the upper bracket portion and the anchor 157.
In certain embodiments, the upper spring element may be arranged
such that it is capable of applying a force onto the anchor.
The damper 152 may be interposed between a wheel assembly 154 of a
vehicle (not shown) and top-mount assembly 151. In the embodiment
in FIG. 15, a suspension coil spring 155 is interposed between the
top-mount bracket 156 and a lower spring perch 157 that is fixedly
attached to the damper housing 158. Upper spring element 159 may be
pre-stressed during the manufacture or assembly of the top-mount
assembly 151 and/or when assembling the vehicle suspension assembly
150.
During manufacture and/or assembly, the upper spring element 159
may be compressed to produce a force that opposes, and at least
partially cancels, the force applied by the piston rod on the
top-mount assembly under static conditions.
FIG. 16 depicts an embodiment of a top-mount assembly and piston
rod described schematically in in FIG. 15. In the embodiment of
FIG. 16, the top-mount assembly includes a bracket having an upper
portion and a lower portion. The lower portion may include a lower
bracket member and an intermediate bracket member, and the upper
portion may include an upper bracket member. One or more
intermediate spring elements 160 may be in contact with the
intermediate bracket member and a strike plate 155. Additionally,
one or more lower spring elements 161 may be in contact with the
lower bracket member and the strike plate 155. One or more upper
spring elements 159 may be in contact with the upper bracket member
and an anchor that is attached to the strike plate 155. The anchor
and strike plate may be arranged such that force applied by the one
or more upper spring elements 159 onto the anchor may be
transmitted to the strike plate 155.
FIG. 16 illustrates the top-mount assembly prior to attachment of
the upper portion and the lower portion. Prior to such attachment,
the one or more upper spring elements 159 are relatively unstressed
(e.g., they apply a force having a magnitude not greater than a
weight of the upper portion of the bracket). Following attachment
of the upper portion to the lower portion, the one or more upper
spring elements 159 may become compressed, such that the one or
more upper spring elements 159 become relatively stressed (e.g.,
they may apply an upward force on the upper portion of the bracket
and a downward force onto the anchor, each force having a magnitude
that substantially exceeds the weight of the upper portion). When
the damper (not shown) is charged, a piston rod 153 that is
attached to the strike plate 155 may apply a static force onto the
strike plate 155 in an upward or substantially upward direction. In
certain embodiments, the length, spring constant, and/or compliance
of the upper spring element 159 may be selected so that, under
static conditions, the static force applied by the piston rod 153
is at least partially balanced by a downward or substantially
downward force applied by upper spring element 159 onto the strike
plate 155. FIG. 17 illustrates a perspective section view of the
top-mount assembly and piston rod shown in FIG. 16.
Although the embodiments described above include a disc shaped
strike plate, one of skill in the art will recognize that the
present disclosure is not so limited and strike plates of any
appropriate configuration can be used in alternative embodiments
without departing from the concepts disclosed herein.
* * * * *